The present disclosure relates to flexible grips for the handles of implements intended to be swung with speed and force such as for example, hammers, axes, and sporting implements such as tennis racquets and golf clubs. The present disclosure particularly relates to such flexible grips for golf clubs where the market trend is toward lighter weight grips and for ways to provide softer, better impact absorbing qualities to the grip.
Because most implement grips, and particularly golf club grips, are made of elastomeric material, it has been found difficult to reduce the weight of the grip by reducing the density of the elastomeric material. Heretofore, fillers and microspheres have been employed in attempts to reduce the weight of the grip; however, these tend to reduce the abrasion resistance and strength of the elastomer. Attempts have also been made to improve the cushioning of the grip by lowering the durometer of the elastomeric material; however, this has resulted in compression set and undesirable reduction in the size of the grip. Furthermore, it is possible for tournament rules for golf to prohibit grips exhibiting permanent deformation.
Heretofore, attempts also have been made to reduce the weight of elastomeric implement grips, particularly golf club grips, by employing a foam spacer between the core and cover of the grip to reduce weight. However, this has resulted in increased difficulty in manufacturing and has been found to be not cost-effective for high volume production.
Additionally, it has been found desirable for marketability to vary the weight, feel and cushioning of the grip locally in certain regions or areas of the grip. Existing golf club grips have been provided with a textured exterior surface which may be formed by dimples resulting from small recesses and grooves in order to provide enhanced traction and firmness near the butt end of the grip and a lesser texture and less firmness in other areas of the grip. Example of such prior art grips are shown in FIG. 1, where a portion of a flexible grip 1 has an open end 2 adapted for being received over an implement handle such as the shaft of a golf club, shown in dashed line 3. The outer surface 1 has spiral texture grooves 4 and texture dimples 5. However, these techniques have been limited in their effectiveness of reducing weight and providing improved cushioning or impact absorption of the grip. As a result of the minimum surface area of contact from the user's hand on the exterior surface of a grip, an exterior surface that has a high concentration of dimples and recesses is not comfortable to the user, particularly on a golf club.
Attempts have also been made to reduce vibrations from impact by employing bands of closely spaced circumferential grooves on the interior surface of the flexible grip 7 as shown in FIG. 2 and described in U.S. Pat. No. 7,048,644.
Thus, it has been desirable to provide a way or means of improving the cushioning and impact absorbing abilities of a flexible elastomeric grip and also to reduce the overall weight of the grip independent of the exterior modifications.